**1. Introduction**

Bananas belong to the genus *Musa* [1] and botanical members of berry [2, 3]. Banana chips are a snack produced from sliced dehydrated or fried banana or plantain. Dried bananas are also ground to make banana flour which has several food applications such as production of stiff dough called *amala ogede* in Nigeria and other West African countries. Singh et al. [4] and FAO [5] reported the worldwide production of bananas in 2012 to be 139.2 million tonnes. According to Singh et al. [4], world banana exports are projected to reach almost 17.9 million tonnes in 2011, and India led the world in banana production, producing around 18% of the worldwide crop of 139 million metric tonnes. It was also reported by Singh et al. [4] that more than 85% of global banana production was produced by small-scale farmers, providing an important source of food and income for the small farm households. In 2016, according to FAOSTAT [6], bananas and plantains were 148 million tonnes globally, with India leading and closely followed by China with a combined total (only for bananas) of 28% of global production. The Philippines, Ecuador, Indonesia and Brazil are other major producers accounting for 20% of the global banana and plantain production (**Table 1**).


#### **Table 1.**

*2016 Production in millions of tonnes.*

Because bananas are highly perishable, there is a need for dehydration of banana to reduce postharvest losses. Among the useful processes used to preserve banana fruits are minimal processing [7–9], refrigeration [10, 11] and dehydration or drying [12–16]. Drying of banana is a useful method to reduce postharvest losses [17, 18] and to improve commercial value of banana. Drying has become necessary to make them available all year round and at locations where they are not produced. In addition to preservation, the reduced weight and bulk of dehydrated banana products decrease packaging, handling and transportation costs [17, 18]. Drying banana can also lead to quality changes such as physical, sensory, nutritional and microbiological. Omolola et al. [19] reported that drying banana gives rise to low or moderate glycemic index (GI) products with high calorie, vitamin and mineral contents.

Drying is the process of moisture removal due to simultaneous heat and mass transfer under controlled conditions to reduce the bulkiness of the fruits [17, 18, 20–23]. It is one of the oldest methods of preservation and widely applied to banana fruits owing to its simplicity, ease of operation and cost-effectiveness. Besides these advantages, drying decreases the bulk of foods by reducing the volume which reduces packaging, handling and storage and transportation costs as well as ease of handling and processing operations [17, 18, 20–25].

Several researchers have carried out studies on drying of bananas, for example, solar drying [26], drying using vacuum [27], foam mat drying [28] and spray drying [29]. Dried banana is a food stock in ripe [30] or unripe maturation state [31]. The dehydration of banana results also in physical modifications as color change [32], shrinkage and porosity [33, 34] and texture [35, 36]. Based on their findings, important dehydration process variables that have influence on drying process and guarantee the obtainment of dried fruits with good quality have been done. Such parameters are appropriate cultivar, pretreatments and drying conditions [37–40].

A lot of research efforts are geared towards the study of drying kinetic of banana fruits. The drying kinetics are usually used to predict the drying behaviour and for optimization of the drying parameters of various foods [41, 42]. Therefore, the chapter focuses on the existing and emerging drying techniques and drying kinetics of banana.

**69**

*Banana Drying Kinetics*

**2. Drying techniques**

which improves efficiency.

**2.1 Natural drying methods**

fied into direct and indirect methods of drying.

dryer could be used to dry banana slices.

*2.1.1 Solar drying*

*2.1.2 Direct method*

*2.1.3 Indirect method*

*DOI: http://dx.doi.org/10.5772/intechopen.84669*

become the goal of modern drying [44–46].

compared with the convective drying in hot air [51–53].

Drying banana is the process of moisture removal due to simultaneous heat and mass transfer under controlled conditions [18, 42, 43]. Drying is the most energyintensive process in the food industry. Therefore, improving drying processes by reducing energy consumption, increasing efficiency of the drying process and providing high-quality products with minimal increase in economic input have

In drying of banana, convective drying in hot air is still the most popular method applied to reduce the moisture content of banana. However, the shortcomings of convective drying in hot air are very long drying period, high-energy consumption, contamination problems, low energy efficiency and high costs, which are not desirable for the food industry [47, 48]. But, the desire to reduce the above problems, as well as to achieve a fast and effective thermal process, led to the use of microwave and dielectric heating methods for banana drying [49, 50]. These drying methods have several advantages such as higher drying rate, shorter drying time, decreased energy consumption and better quality of the dried products when

Drying methods are divided into natural and artificial methods of drying. The natural method of drying involves the use of energy from the sun to remove moisture from banana fruits. The major shortcoming of this method is that it depends on weather conditions and is highly inefficient [54]. Artificial method of drying uses mechanical devices to improve drying efficiency of the method [55]; this leads to products of better quality. In addition controlling of various factors involved in the drying process such as temperature, drying air flux and time of drying is also possible. Artificial drying is done with the help of mechanical or electrical equipment

Sun is as old as the universe itself and is an inexhaustible and free source of energy, utilized for drying of banana since ancient times. Solar drying can be classi-

This is a traditional method which involves the sunlight to dry banana. Banana to be dried is left exposed to the sun for several days to achieve the desired moisture content. This is very common in developing countries where fuel is scarcely available to farmers due to high cost; open sun drying is the most popularly used method of drying since it is simple and only requires sunlight [56]. However, the major problems faced by open-air sun drying are insect infestation, dust and dirt contamination, long time for drying, overheating due to direct exposure, quality deterioration and low rate of transmission of heat due to condensation of the evaporated moisture [57]. In order to improve on the sun drying method, a simple form of solar

Indirect solar drying involves the use of solar dryer to overcome the problems encountered by the direct method of drying. Different types of indirect solar dryers
